Finerfilters 4 Stage Triple 50GPD Aquarium Reverse Osmosis with 417g DI Resin For Drop-In Cartridge Replacement Water Filters Removes very high levels of most impurities from the water, ideal for filtering tap water for your Aquarium. Includes: 1 x Sediment Pre-Filter 1 x 5 Micron Carbon Block 1x 50GPD Membrane 1 x Bag of 417g DI Resin Please note: this is for RO replacement filters only. Fittings are not included. PTFE tape will be required when installing fittings.